The present invention generally pertains to electronic data processing systems and is particularly directed to a system for transferring digital data between a host device, such as a computer, and a recording medium.
It is common to transfer data accumulated in a computer to a back-up recording medium, such as a recording tape or a disk, when the computer is to be used for tasks not requiring such data. When such data is again required, it is transferred back to the computer from the recording medium.
Typically such a data transfer system includes a buffer memory having a matrix of storage locations for storing digital data; a write interface unit for transferring data to a target recording medium for recording; a read interface unit for reading and processing data from a target recording medium; and a buffer interface control unit for transferring data between the host device and the buffer memory, for transferring data from the buffer memory to the write interface unit during a writing mode of operation, and for transferring data from the read interface unit to the buffer memory during a retrieval mode of operation. The data transfer between the host device and the buffer memory is asynchronous with the data transfer between the buffer memory and the write and read interface units.
During the course of transferring the data from the host unit to the target recording medium and then back to the host unit errors are sometimes induced in the data. To provide for the correction of such errors, error detection code characters and error correction code characters are calculated for the data and interspersed with and recorded with the data on the target recording medium in accordance with a predetermined recording format. During the retrieval mode, the data read by the read interface unit is processed in accordance with the recorded error detection code characters to detect any errors in the read data. When errors are detected they are corrected in accordance with the recorded error correction code characters.
It is the object of the present invention to provide a data transfer system that efficiently transfers data for recording in a format wherein the data is interspersed with error detection code characters and error correction code characters pertaining to the transferred data.